Installation for the treatment and movement of liquid metals

ABSTRACT

An installation for the treatment and movement of liquid metals prior to casting, comprising, in succession, at least one metal smelter, involving an electromagnetic pump which forces back metal being smelted toward the solid metal inserted into the furnace; at least one ladle for keeping the metal in the liquid state, at least one degassing furnace, which supplies at least one work station and which involves an electromagnetic metal stirring pump. Electromagnetic or similar pumps are used for moving the liquid from the smelter to the ladle, degassing furnace and work station. This installation is particularly useful for treating and moving aluminum, zinc and magnesium.

Carbonnel et a1. I

1 51 May 7, 1974 [5 INSTALLATION FOR THE TREATMENT 3,572,671 v 3/1971Worner 266/34 v AND MOVEMENT OF LIQUID METALS 3,558,121 1/1971 Lenne....266/34 V 3,618,917 11/1971 Freg rilgspn. .1. .266/3.4 T Inventors: HenriCarbonnel, y; Jean-Paul 3,606,291 9/1971 Schneider: "Ts/49' Le Frere,Villejuif, both of France 2,224,982 12/1940 Morin 164/49 1 1 Assignee=(troupe-mm Atomique 418mm 313233352 3/132; 512123;;z;';1:::::..::::::::::::522/333 Atlantique, Le Pless1s Robinson, France PrimaryExaminer-Gerald A. Dost [22] Filed: June 27, 1972 Attorney, Agent,'0rFirmSughrue, Rothwell, Mion, 21 Appl. No.: 266,800 Mapeak Related U.S.Application Data ABSTRACT [63] Continuation-impart of Ser. No. 136,078,April 21, v

1971, abandoned. An installation for the treatment and movement of liq-I uid metals prior to casting, comprising, in succession, [30] ForeignApplication Priority Data at least one metal smelter, involving anelectromag- Apr. 21, 1970 France 70.14468 "etic P which forces hackmetal being Smehfid Apr. 7, 1971 France 71.12355 toward the Solid metalinserted into the furnace; at least one ladle for keeping the metal inthe liquid 52 U.S. C1. 266/34 v, 75/49 State, at least one degassingfurnace, which pp at [51] Int. Cl. .1 C21c 7/10 least one work stationand which involves an electro' 58 Field Of Search 75/49; 164/49, 250;magnetic metal-Stirring Pump. Electromagnetic 9r 266/34 A, 34 T3 34 Vilar pumps areuscd for moving the liquid from the smelter to the ladle,degassing furnace and work sta- [56] References Cited tion. Thisinstallation is particularly useful for treating UNITED STATES PATENTSand moving aluminum, zinc and magnesium. 2,587,793 10 Claims, 2 DrawingFigures 3/1952 waldronm 266/34 .V

A l I O0 1 l This is a continuation in part of U.S. application Ser. No.136,078 filed Apr. 21, 1971, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an installationfor the treatment and movement of liquid metals for casting purposes orthe like.

In the field of metallurgy, e. g., metals such as aluminum, zinc, or thelike,'a certain number of problems and technical restrictions come up inthe various phases through which the solid metal is brought to itsutilization in the liquid state, for example, for casting purposes.Urgent considerations of cost and output, in particular, create the needfor over coming these hazards as best possible.

In particular, attempts are made to reduce to a minimum the ignitionlosses resulting from the smelting of the raw material coming in theform of ingots or waste, such as chips, shavings, droppings, or others.

Also, such materials must be smelted within a minimum period of timeunless one wishes to limit the hourly casting rate and thus increase theperiod of depreciation of the equipment and particularly of the smeltingfurnace.

Furthermore, the movement of the liquid metal from the smelter to afurnace or a holding ladle must likewise be accomplished as quickly aspossible, in other words, at a rather high flow rate.

On the other hand, it is also necessary to degas and rapidly purify themetal in an installation in a vacuum or through treatment with a gassuch'as nitrogen or chlorine, in order to produce a good metal whichwill not have any impurities and which will then be moved on finally towork stations consisting particularly of continuous or semicontinuouscasting installations or even casting ladles or foundry molds.

Installations used so far entail a certain number of inconveniences.

In particular, the liquid metal is moved from the smelter to the holdingladle by gravity and this kind of operation requires either that thesmelters be tipped or that the various work stations involved be locatedon different levels. Such an operation necessarily makes for a limitedflow rate and this leads to appreciable loss of time and involves heavyinvestments.

Since the smelted metal supply for the work stations is accomplished bygravity in the manner indicated above, the metal flow rate is thusregulated either manually or by using compressed air. It follows fromthis that such installations require a large work force which leads to amajor increase in the cost of cast ingots.

- SUMMARY OF THE INVENTION This invention makes it possible to remedythese inconveniences and its object is an automatic installation for thetreatment and movement of liquid metals prior to their casting, whichwill make it possible to solve the above mentioned technical problemsand restrictions, while-offering great flexibility in operation and highreliability.

The liquid metal treatment and movement installation of the presentinvention involves several stations arranged in succession, one afterthe other, and inranged on the same horizontal plane, and, on the otherhand, by the fact that the treatment means are incorporated in themovement means.

BRIEF DESCRIPTION- or THE DRAWINGS Other features and advantages of theinvention will emerge from the following description given here purelyby way of illustration and without any limitations, referring to theattached drawing where:

FIG. 1 is a schematic view of a liquid metal treatment and movementinstallation according to the invention, and

FIG. 2 is a schematic view of a variation of the installation accordingto the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to FIG. 1, a liquidmetal treatment and movement installation includes, in succession, asmelter 1, a furnace or ladle 2 for keeping the liquid metal in thesmelted state, and a vacuum degassing furnace 3.

Smelter l is of the fixed, non-tipping type and continuously receivesmetal in the solid state, for example, in the form of chips 4 through aspout 5 which empties into an inclined portion 6 of the smelter. Furthermore', an electromagnetic pump 7, immersed in the smelted metal 8,continuously forces liquid metal back into contact with the chips 4,thus guaranteeing their continuous smelting, while the liquid metalresulting from this flows along the inclined plane 6.

This kind of fusion or smelting makes it possible to reduce the ignitionloss while guaranteeing, on the one hand, the rapid burying of the solidmetal and, on the other hand, the energetic stirring of the metal bathin fusion by means of pump 7. This further leads to the acceleratedsmelting of the metal, as well as to a reduction in the time duringwhich the metal is exposed to the oxiding action of the atmosphere. Onecan advantageously permanently leave in smelter 1 a certain quantity ofliquid metal which-constitutes a heat-steadying factor and thus promotessmelting.

FIG. 2 shows a device in which the smelter acts at the same time as atreatment furnace.

An external electromagnetic pump 7 pumps the liquid metal and poursliquid metal over the chips 4. This pump is arranged outside the liquidmetal each time the latter melts only at a very high temperature.

An electromagnetic treatment pump 12' receiving a gaseous current 15'injects the liquid metal into a bottomless casting 16'.

As in the case of the pump 7 because of the high melting point of theliquid metal, it can be necessary to install the pump 12 outside.

The liquid metal 8 from smelter l ismoved continuously toward furnace ofholding ladle 2 by means of an electromagnetic pump 9 which makes itpossible advantageously to insure a constant as well as a high flowrate, which cannot be accomplished by using the conume, sothat theliquid metal will permanently remain at an essentially constanttemperature.

The liquid metal moved along by pump is then degassed in furnace 3 whichis linked to a vacuum pump 11. The furnace 3 involves an immersedelectromagnetic pump 12 which insures the beneficial stirring of theliquid metal-bath 8, which leads to an increase in the degassing speed.Finally, an electromagnetic pump 13 moves the liquid metal toward thework station and especially the casting stations, the pump 13advantageously making it possible to obtain a predetermined quantity ofliquid metal at a variable and easily programmed flow rate establishedby device 21.

It must be noted that, in certain cases, vacuum pump 11 can beeliminated; in such a case, the degassing of the liquid metal isreplaced by treatment with a gas such as nitrogen orchlorine or by aneutral gas injected by duct 15 into the liquid metal inside pump 12 orinto pump 9 through pipe 20. v

In this latter case, the gas and the liquid metal are reinjected by thepump below the level of the liquid metal into a bottomless casing 16.The treatment gas moves along the slag l7 and the gases that areoccluded in the upper portion of the casing, and the purified liquidmetal is then gathered in its lower portion without any contact with theatmosphere of the furnace.

It should also be noted that, in certain cases, it willbe advantageousto combine holding ladle 2 and degassingfurnace 3 into a single furnace.

' It should likewise be noted that it may be advantageous in certaincases to combine smelting furnace 1 holding ladle 2, and degassingfurnace 3, into a single furnace.

In the case of FIG. 2, the metal can undergo a double treatment,simultaneously by the pump 12' and the pump 7'. v

' In a device according to FIG. 2, it can be a great advantage not toprovide the holding ladle, the furnace alone insuring simultaneously thefunctions fulfilled by the volumes 1, 2 and 3 of FIG. 1.

It is also noted that, in such an installation, the metal 'ispermanently protected from the air, which limits its oxidation, on theone hand, and the possible absorption of gas, on the other hand.

This advantage is guaranteed especially as a result of the use of pumpsof the electromagnetic type which make it possible to move the liquidsin entirely sealed circuits and which therefore are very tightly sealed.

The installation involved in this invention may be used in all caseswhere the treatment and movement of liquid metal must be accomplished inan automatic fashion and at a predetermined flow rate.

In particular, it is advantageously employed especially with metals suchas aluminum, zinc and magnesium.

Although the device just described seems to be the most advantageous forthe employment of the invention in a particular industrial situation, itwill be understood that variousmodifications may be made in it withoutgoing beyond its framework, that some of its elements can be replacedwith others that can perform the same technical function, for example,evacuation pump 13 can, at the same time, have the same gas treatmentfunction as pump 12 or, when furnaces l, 2 and 3 are replaced with asingle furnace, the gas treatment function can be accomplished by asingle pump such as pump 9.

What is calimed is:

1. In a liquid metal treatment and movement installation involvingseveral stations arranged in succession, including at least one metalsmelter, one holding ladle for maintaining the metal in the liquidstate, and one vacuum degassing furnace, the installation feeding atleast one work station, the improvement wherein: said smelter, saidladle and said degassing furnace are located on the same horizontalplane such that the molten metal contents within said stations are atthe same height, electromagnetic pumps couple respective stations formoving liquid metal therebetween and wherein at least one of saidelectromagnetic pumps fluid coupling respective stations furthercomprises means for. treating the liquid metal being pumped thereby.

2. Installation according to claim 1, wherein the smelter comprises anelectromagnetic pump which continuously sprays the smelted metal uponthe solid metal being inserted into the smelter.

3. Installation according to claim 2, wherein said electromagnetic pumpis immersed in said smelted metal.

4. Installation according to claim 2, wherein said electromagnetic pumpis arranged outside' of said I smelter.

mined by the desired level of the metal in said ladle.

6. Installation according to claim 1, wherein said degassing furnaceinvolves an immersed electromagnetic pump which stirs the liquid metal.

7. Installation according to claim 1, wherein said'degassing furnaceinvolves an'external electromagnetic pump which stirs the liquid metal.

8. Installation according to claim 6, wherein said immersedelectromagnetic pump simultaneously per forms a stirring function andtreats the liquid metal to gasses such as chlorine or nitrogen or aneutral gas.

9. Installation according to claim 5, wherein the electromagneticpumpwhich moves the liquid metal from the smelter to the holding ladleat the same time treats the liquid metal to gasses such as chlorine ornitrogen or a neutral gas.

l0.'lnstallation according to claim 1 further comprising program meansfor controlling flow through the electromagnetic pump, which moves theliquid metal from the degassing furnace to the working station.

2. Installation according to claim 1, wherein the smelter comprises anelectromagnetic pump which continuously sprays the smelted metal uponthe solid metal being inserted into the smelter.
 3. Installationaccording to claim 2, wherein said electromagnetic pump is immersed insaid smelted metal.
 4. Installation according to claim 2, wherein saidelectromagnetic pump is arranged outside of said smelter. 5.Installation according to claim 1, wherein the flow rate of theelectromagnetic pump that moves the liquid metal from the smelter to theholding ladle is determined by the desired level of the metal in saidladle.
 6. Installation according to claim 1, wherein said degassingfurnace involves an immersed electromagnetic pump which stirs the liquidmetal.
 7. Installation according to claim 1, wherein said degassingfurnace involves an external electromagnetic pump which stirs the liquidmetal.
 8. Installation according to claim 6, wherein said immersedelectromagnetic pump simultaneously performs a stirring function andtreats the liquid metal to gasses such as chlorine or nitrogen or aneutral gas.
 9. Installation according to claim 5, wherein theelectromagnetic pump which moves the liquid metal from the smelter tothe holding ladle at the same time treats the liquid metal to gassessuch as chlorine or nitrogen or a neutral gas.
 10. Installationaccording to claim 1 further comprising program means for controllingflow through the electromagnetic pump, which moves the liquid metal fromthe degassing furnace to the working station.